A prior art notching machine of the kind as herein referred is described in German OS No. 29 31 410, published Apr. 30, 1981. An upper knife is thereby designed as a thin singular blade and directly attached to a vertically moving ram of the machine. A lower knife is formed of two or more singular blades and attached by means of a matrix to a matrix holder of the machine table. Above this matrix holder a guide for the workpieces to be notched is formed of a base plate and a support plate, said guide having adjustable stoppers with which the workpieces are brought into contact for an accurate notching. The support plate, in the cutting path of the upper knife, is provided with a cutting out having an angle of 90.degree. and may be turned on the base plate around an axis of rotation provided near the nose of the knives. By means of this prior notching machine, as a result of two successive working strokes of the ram and an intermediate turning of the guide in the interval from a first resting position adjusted by means of stoppers corresponding to a particularly desired angle into an equally adjusted second resting position, it is accordingly possible to provide notchings in workpieces of any desired size of angle up to a maximum of 90.degree.. For each of the two working strokes, optimum cutting relationships may be established between the cutting edge of the upper blade and the two alternatively cutting actions of the at least two lower blades. However, this prior notching machine has a disadvantage that with a succession of two working strokes of the ram the workpieces are turned together with the guide so that particularly with larger workpieces that regularly project forwardly from the front of the machine table a constant threat of injury is present to the worker standing in front of the machine. With greater angles and a greater rotating mass of the workpieces the adjustable stoppers for the two resting positions of the guide are also correspondingly more demanded so that the notching may become imprecise when the stoppers are not reset in time.
This invention deals with the object of providing a notching machine allowing the notching of workpieces of even larger dimensions with any desired angle also larger than 90.degree. and each carried out by two working strokes of the ram with less danger of injury for the worker. The notching machine shall also allow a simple adjustment for a change over from one to any other desired notching angle.
The advantages obtained from the provision according to this invention of two commonly turnable set collars as attachment means for the upper and lower knives and from the use of the lower set collar as an auxiliary table is mainly to be recognized in the fact that the workpieces now no longer change their relative position with respect to the machine table between every two successive working strokes of the ram needed for each notching of a workpiece. With the turning of the two set collars from a first resting position adjusted to a particularly desired notching angle to an adjusted second resting position the lower set collar passes below the workpieces which preferably are held in contact with table stoppers for an accurate notching. Since the common turning path of these two set collars may easily be changed, any change from one to another desired notching angle may correspondingly be easily carried out. The provision of the upper set collar thereby also offers the possibility to also form the upper knife of two singular blades with a corresponding vertex of 30.degree. in order to be able to notch workpieces with only one working stroke of the ram with an angle of 30.degree. and if desired with two working strokes with an angle up to 120.degree. or more.